LinkLoader.cpp

/*
 * Copyright (C) 2011 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions are
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 * in the documentation and/or other materials provided with the
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 * this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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#include "config.h"
#include "LinkLoader.h"

#include "CSSStyleSheet.h"
#include "CachedCSSStyleSheet.h"
#include "CachedResourceLoader.h"
#include "ContainerNode.h"
#include "DNS.h"
#include "Document.h"
#include "Frame.h"
#include "FrameView.h"
#include "LinkRelAttribute.h"
#include "Settings.h"
#include "StyleResolver.h"

#if ENABLE(LINK_PRERENDER)
#include "PrerenderHandle.h"
#include "Prerenderer.h"
#endif

namespace WebCore {

LinkLoader::LinkLoader(LinkLoaderClient* client)
    : m_client(client)
    , m_linkLoadTimer(this, &LinkLoader::linkLoadTimerFired)
    , m_linkLoadingErrorTimer(this, &LinkLoader::linkLoadingErrorTimerFired)
{
}

LinkLoader::~LinkLoader()
{
    if (m_cachedLinkResource)
        m_cachedLinkResource->removeClient(this);
}

void LinkLoader::linkLoadTimerFired(Timer<LinkLoader>* timer)
{
    ASSERT_UNUSED(timer, timer == &m_linkLoadTimer);
    m_client->linkLoaded();
}

void LinkLoader::linkLoadingErrorTimerFired(Timer<LinkLoader>* timer)
{
    ASSERT_UNUSED(timer, timer == &m_linkLoadingErrorTimer);
    m_client->linkLoadingErrored();
}

void LinkLoader::notifyFinished(CachedResource* resource)
{
    ASSERT_UNUSED(resource, m_cachedLinkResource.get() == resource);

    if (m_cachedLinkResource->errorOccurred())
        m_linkLoadingErrorTimer.startOneShot(0);
    else 
        m_linkLoadTimer.startOneShot(0);

    m_cachedLinkResource->removeClient(this);
    m_cachedLinkResource = 0;
}

bool LinkLoader::loadLink(const LinkRelAttribute& relAttribute, const String& type,
                          const String& sizes, const KURL& href, Document* document)
{
    // We'll record this URL per document, even if we later only use it in top level frames
    if (relAttribute.m_iconType != InvalidIcon && href.isValid() && !href.isEmpty()) {
        if (!m_client->shouldLoadLink()) 
            return false;
        document->addIconURL(href.string(), type, sizes, relAttribute.m_iconType);
    }

    if (relAttribute.m_isDNSPrefetch) {
        Settings* settings = document->settings();
        // FIXME: The href attribute of the link element can be in "//hostname" form, and we shouldn't attempt
        // to complete that as URL <https://bugs.webkit.org/show_bug.cgi?id=48857>.
        if (settings && settings->dnsPrefetchingEnabled() && href.isValid() && !href.isEmpty())
            prefetchDNS(href.host());
    }

#if ENABLE(LINK_PREFETCH)
    if ((relAttribute.m_isLinkPrefetch || relAttribute.m_isLinkSubresource) && href.isValid() && document->frame()) {
        if (!m_client->shouldLoadLink())
            return false;
        ResourceLoadPriority priority = ResourceLoadPriorityUnresolved;
        CachedResource::Type type = CachedResource::LinkPrefetch;
        // We only make one request to the cachedresourcelodaer if multiple rel types are
        // specified, 
        if (relAttribute.m_isLinkSubresource) {
            priority = ResourceLoadPriorityLow;
            type = CachedResource::LinkSubresource;
        }
        ResourceRequest linkRequest(document->completeURL(href));
        
        if (m_cachedLinkResource) {
            m_cachedLinkResource->removeClient(this);
            m_cachedLinkResource = 0;
        }
        m_cachedLinkResource = document->cachedResourceLoader()->requestLinkResource(type, linkRequest, priority);
        if (m_cachedLinkResource)
            m_cachedLinkResource->addClient(this);
    }
#endif

#if ENABLE(LINK_PRERENDER)
    if (relAttribute.m_isLinkPrerender) {
        ASSERT(!m_prerenderHandle);
        m_prerenderHandle = document->prerenderer()->render(href);
    }
#endif
    return true;
}

void LinkLoader::released()
{
    // Only prerenders need treatment here; other links either use the CachedResource interface, or are notionally
    // atomic (dns prefetch).
#if ENABLE(LINK_PRERENDER)
    if (m_prerenderHandle) {
        m_prerenderHandle->cancel();
        m_prerenderHandle.clear();
    }
#endif
}

}